Rafflesiaceae Dum.
Including Apodanthaceae Van Tiegh., Cytinaceae Brongn., Mitrastemonaceae Mak., Patmaceae Schultz-Schultzenst., Pistiaceae C.A. Agardh (p.p.)
Habit and leaf form. Very peculiar endoparasitic herbs. Plants of very peculiar vegetative form; the vegetative parts filamentous, or fungoid. Leaves much reduced (at the bases of flowering stems, or beneath the flower), or absent. Plants rootless; totally parasitic (permeating the host tissues, with only the flowers or the flowering stems exserted). On roots of the host (mostly), or on aerial parts of the host (less often). Leaves alternate, or opposite, or whorled (usually); membranous (scales).
Leaf anatomy. Stomata absent.
Stem anatomy. Secondary thickening absent (the vascular system vestigial or absent). Xylem when present, without vessels. Sieve-tube plastids when present, lacking both protein and starch.
Reproductive type, pollination. Plants hermaphrodite (rarely), or monoecious, or dioecious (?). Entomophilous.
Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’; small to very large (including Rafflesia arnoldii, with the largest known flowers — up to 1 m in diameter); malodorous (often), or odourless; regular; cyclic.
Perianth sepaline, or petaline; 4, or 5(–10); free, or joined (often forming a tube); 1 whorled; fleshy, or non-fleshy (usually imbricate, rarely valvate). Calyx (if the perianth so interpreted) 4, or 5(–10); 1 whorled; polysepalous, or gamosepalous; regular; fleshy (often, more or less), or non-fleshy; imbricate (usually), or valvate (rarely).
Androecium of male flowers 5–100 (to ‘many’). Androecial members free of the perianth; united with the gynoecium (or at least, with the stylar column); free of one another (in 1–several cycles), or coherent (via the connate filaments, forming a tube round the stylar column); 1–4 whorled (to ‘several’). Androecium exclusively of fertile stamens. Stamens 5–100 (to ‘many’); filantherous, or with sessile anthers. Anthers dehiscing via longitudinal slits (in the less modified forms), or dehiscing via pores, or dehiscing transversely; unilocular, or bilocular; tetrasporangiate. Microsporogenesis simultaneous. Pollen shed as single grains. Pollen grains aperturate, or nonaperturate (e.g. Rafflesia); when aperturate, 2–3(–4) aperturate; colpate, or porate; 2-celled.
Gynoecium (in female flowers) 4–8 carpelled. The pistil 1–20 celled. Gynoecium syncarpous; synstylovarious, or eu-syncarpous (the stout, columnar style expanded into an often large, complex disk, with stigmatal projections); partly inferior, or inferior. Ovary 1 locular, or 3–10(–20) locular (by deep intrusion of the placentas). Styles 1; apical. Placentation when unilocular, parietal (the placentas variously intruded or branched); when plurilocular, parietal (or with the very minute ovules covering the inner surfaces of the partitions). Ovules in the single cavity 50–100 (‘very numerous’, and very minute); 25–100 per locule (‘very numerous’); non-arillate; orthotropous (Cytineae), or hemianatropous to anatropous; unitegmic (Mitrastemonoideae), or bitegmic (Apodantheae, and the Rafflesieae and Cytineae with rudimentary outer integuments); seemingly universally tenuinucellate. Outer integument not contributing to the micropyle. Embryo-sac development Polygonum-type. Antipodal cells formed; 3; not proliferating; persistent. Synergids pear-shaped. Endosperm formation cellular (Mitrastemon), or nuclear (Cytinus, Rafflesia, Pilostyles). Embryogeny caryophyllad, or solanad (?).
Fruit fleshy, or non-fleshy; dehiscent, or indehiscent; a berry, or a capsule. Capsules (when capsular) splitting irregularly. Gynoecia of adjoining flowers combining to form a multiple fruit, or not forming a multiple fruit. Seeds endospermic, or non-endospermic (Cytinus); minute. Embryo rudimentary at the time of seed release.
Geography, cytology. Temperate (warm), or sub-tropical to tropical. South and Central America and Southwest U.S.A., Mediterranean and Middle East, Southern Africa and Madagascar, Southeast Asia and Malaysia, Australia. X = 12.
Taxonomy. Subclass Dicotyledonae; Crassinucelli. Dahlgren’s Superorder Santaliflorae; Santalales (cf. Hydnoraceae). Cronquist’s Subclass Rosidae; Rafflesiales. APG (1998) oddment family, or family of uncertain position at the highest group level (Cytinaceae, Mitrastemonaceae). Species 50. Genera 9; Apodanthes, Bdallophytum, Berlinianche, Cytinus, Mitrastemon, Pilostyles, Rafflesia, Rhizanthes, Sapria.
Illustrations. • Technical details (Pilostyles). • Technical details (Apodanthes, Cytinus, Rafflesia).
Cite this publication as: ‘L. Watson and M. J. Dallwitz (1992 onwards). The Families of Flowering Plants: Descriptions, Illustrations, Identification, and Information Retrieval. Version: 14th December 2000. http://biodiversity.uno.edu/delta/’. Dallwitz (1980), Dallwitz, Paine and Zurcher (1993, 1995, 2000), and Watson and Dallwitz (1991) should also be cited (see References).
